Power Supply Redundant PSU modules for high power internal AC -> 12V?


Virtual Realist
Original poster
May 11, 2015
Reading PCPer's review of a redundant PSU, a line jumped out at me:
The modular power supplies only produce +12V and +5VSB, so the +3.3V, +5V, and -12V outputs are all generated on the main PCB inside the enclosure. Current limiters are used to turn the single +12V output from the modular power supplies into three 16A +12V outputs.
Each of those FSP520-20RGGBB1 modules is a 520W 92% efficienct single-rail 12V supply, feeding via a card-edge connector (AKA nice big solder pads that sadly lack strain-relief).
While FSP don't publish the dimensions of the FSP520-20RGGBB1 modules directly, their face dimensions are at a maximum 1/2 of the face dimension of the carrier, or a maximum of 75mm x 75mm x 190mm, or 1.07L. Probably a little less than this (I'd guess closer to 60x60x180, or 0.65L).

The drawback is that tiny little screamer fan, though it is mounted externally so easily removed and could be replaced with a larger ducted fan or shared airflow fro ma case fan, and the need to 'fool' the module into turning on outside of its intended housing. The card-edge connector could be used as a pair of big solder pads, or a card-edge socket used to make it easier to remove/install the PSU (said connector could even be integrated into a DC-DC solution.

It's also not the cheapest option: the FSP Twins is $400 on its own, making the module cost somewhere around or just below $200 (two modules plus the carrier).


Lord of the Boards
SFFn Staff
May 9, 2015
I've looked at these for a while on TPU (ads) and also noticed the 12V output, which makes sense for this concept. Most enterprise rendundant power supplies do this too and they're available well over 1000W and sometimes even available relatively cheap. But the fan, proprietary form and sometimes limited availability is not easy to overcome.

I've looked at that specific PSU for various projects, but I can't justify it ever. There is no scenario where I might blow a PSU and care more that I can continue doing what I'm doing. Maybe for people doing live entertainment like P/A and video mixing, but I'm guessing those markets already have their bases covered.